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3 years ago

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A scientist designed a foam container to help keep frozen foods from melting. Which best explains how the foam works? It removes

thermal energy from the air inside the container. It removes thermal energy from the frozen foods inside the container. It reduces the amount of thermal energy that is transferred from inside to outside the container. It reduces the amount of thermal energy that is transferred from outside to inside the container.

1 answer:

Allushta [10]3 years ago

6 0

Answer:

the foam an insulator............

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A man is standing on a platform that is connected to a pulley arrangement, as the drawing shows. By pulling upward on the rope w

leonid [27]

Answer:

The pulling force that the man should apply to create an upward acceleration of $1.20m/s^{2}$ is $P=621.5N$

Explanation:

Hi

As it shows in the drawing at the end, we have that the total mass of the man plus the platform is $113 kg$ , then the force downward $W$ is $W=mg=113Kg*9.8m/s^{2}=1107.4N$ .

Due the man needs to do a pulling force upward capable of lifting himself and the platform with an acceleration of $1.20m/s^{2}$ , this force should create an acceleration greater than gravity by $1.20m/s^{2}$ . then $a_{up}=g+1.2m/s^{2}=9.8m/s^{2}+1.2m/s^{2}=11m/s^{2}$ . Therefore the force should be $P_{up}=ma_{up}=113kg*11m/s^{2}=1243N$ .

Finally, as we have a pulley arrangement connected to the platform, it gives the man a mechanical advantage, so he has to do only half of that upward force

, therefore $P=\frac{1243N}{2}=621.5N$ .

8 0

3 years ago

HELP, what are 2 chemical properties of Tungsten.

GarryVolchara [31]

Answer:

Molybdenum and seaborgium

3 0

3 years ago

Read 2 more answers

Two steamrollers begin 115 mm apart and head toward each other, each at a constant speed of 1.10 m/sm/s . At the same instant, a

NeX [460]

Answer:

The distance of fly travel is 115.06 m.

Explanation:

Given that,

Distance = 115 mm

Speed = 1.10 m/s

Speed of fly = 2.20 m/s

We need to calculate the relative speed

Using formula of relative speed

$v=v_{1}+v_{2}$

Put the value into the formula

$v=1.10+1.10$

$v=2.20\ m/s$

We need to calculate the time for the two steamrollers to meet each other

Using formula of time

$t=\dfrac{d}{v}$

Put the value into the formula

$t=\dfrac{115}{2.20}$

$t=52.3\ sec$

We need to calculate the distance of fly travel

Using formula of distance

$d=vt$

Put the value into the formula

$d=2.20\times52.3$

$d=115.06\ m$

Hence, The distance of fly travel is 115.06 m.

3 0

3 years ago

Why are you able to make someone on a swing have very large swings by only exerting very small forces on them?

Allisa [31]

Because almost all of the force is done by the weight of the person and the mechanism of the swing itself, when you push someone you only give them an increase in velocity, the acceleration comes from the weight at first and then from gravity when the person is coming down, which is why we bend our legs when coming down

3 0

3 years ago

Two electrons with a charge of magnitude 1.6×10-19 C in an atom are separated by 1.5×10-10 m, the typical size of an atom. What

vesna_86 [32]

Answer:

$1.02\cdot 10^{-8} N$ , repulsive

Explanation:

The magnitude of the electric force between two charged particles is given by Coulomb's law:

$F=k\frac{q_1 q_2}{r^2}$

where:

$k=8.99\cdot 10^9 Nm^{-2}C^{-2}$ is the Coulomb's constant

$q_1, q_2$ are the two charges of the two particles

r is the separation between the two charges

The force is:

- repulsive if the two charges have same sign

- Attractive if the two charges have opposite signs

In this problem, we have two electrons, so:

$q_1=q_2=1.6\cdot 10^{-19}C$ is the magnitude of the two electrons

$r=1.5\cdot 10^{-10} m$ is their separation

Substituting into the formula, we find the electric force between them:

$F=(8.99\cdot 10^9)\frac{(1.6\cdot 10^{-19})^2}{(1.5\cdot 10^{-10})^2}=1.02\cdot 10^{-8} N$

And the force is repulsive, since the two electrons have same sign charge.

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3 years ago